It appears a meltdown may be in process according to CNN (posted on CNN March 12, 2011 10:51 p.m. EST):
http://www.cnn.com/2011/WORLD/asiapcf/03/12/japan.nuclear/index.html?hpt=T1
Excerpt:
Tokyo (CNN) -- A meltdown may have occurred at at least one nuclear power reactor in Japan, the country's chief cabinet secretary, Yukio Edano, said Sunday, adding that authorities are concerned about the possibility of another meltdown at a second reactor.
"We do believe that there is a possibility that meltdown has occurred. It is inside the reactor. We can't see. However, we are assuming that a meltdown has occurred," he said about the No. 1 reactor at the Fukushima Daiichi nuclear facility.
"And with reactor No. 3, we are also assuming that the possibility of a meltdown as we carry out measures," Edano said.
Edano's comments confirm an earlier report from an official with Japan's Nuclear and Industrial Safety Agency, who said, "we see the possibility of a meltdown."
"There is a possibility, we see the possibility of a meltdown," said Toshihiro Bannai, director of the apan's Nuclear and Industrial Safety Agency international affairs office, in a telephone interview from the agency's headquarters in Tokyo. "At this point, we have still not confirmed that there is an actual meltdown, but there is a possibility."
A meltdown is a catastrophic failure of the reactor core, with a potential for widespread radiation release.
Though Bannai said engineers have been unable to get close enough to the core to know what's going on, he based his conclusion on the fact that they measured radioactive isotopes in the air Saturday night.
"What we have seen is only the slight indication from a monitoring post of cesium and iodine," he said. Since then, he said, plant officials have injected sea water and boron into the plant in an effort to cool its nuclear fuel and stop any reactions.
